switchtesting , (june13th2015:additional test by MRsDNF in post#44)

I got these two 100W 0.5Ohm resistors in the mail yesterday, so I could make me a test-load to do current tests now, I wanted that for a while. I screwed them down on a MCU-heatsink with fan, and wired them parallel, now it is a maximum of 200W test-load, it should handle currents up to 28A.

This thread about a new 6A switch that I found on ebay made me want to test a few switches, I asked other BLF-members how a switch test should look like (the concensus was that long periods on high amps is what kills a switch, not the number of clicks), and tonight I started some testing on three switches that I had and will destroy for some greater good, I hope... For completeness I would have liked to include the Tofty switch, but I don't have one, and Scaru did some pretty tough testing on that one already, actually more thorough than I am doing with these.

This is the test-rig (oven tray science!):

The circuit goes from powersupply to the test-load to the three switches in series back to the power supply, all thick copper wiring, almost everything soldered thoroughly together. The three switches are on a ceramic tile, not that I expect fire or anything serious when a switch blows, but it will run for many hours so I can not continuously guard the test.

The three switches are: a small Omten switch, a larger Omten switch, and the ebay-6A switch.

I started the test tonight at 3A (the power supply will give 3A regardless of any resistance changes, up to 16V), I think all three switches would survive lower currents than that. I have run the switches for four hours now and they all live. Tomorrow I will do four hours on 6A and four hours on 10A. Any switch surviving that will get 16A sometime this weekend.

Measuring the voltage over the switches at 3A already shows differences: the bigger the switch, the lower the voltage (and thus the resistance), I also measured the voltage over a piece of the copper wire:

Actually the voltage (resistance) varies after each switch-on, and after each switch-on it also changes a bit, usually it starts a bit higher, and it settles at a bit lower voltage after 10-20 seconds. Here's some voltages, at 3A I did 10 switch-on cycles on each switch and noted the voltage reading (you can calculate resistance and power generated in the switch yourself! )

*small Omten switch: 25 23 17 20.5 18.7 15.9 15.9 15.9 18.1 23 mV

*large Omten switch: 17 15 14.9 18 16 15.5 15.3 15.3 15.3 15.3 mV

*6A ebay switch: 5 5.5 6.4 5.4 7 7.5 6.2 5.2 5.8 6.3

After the 4 hours at 3A, I did another 10 clicks to see if the resistance had changed:

*small Omten switch after 4 hours at 3amps: 37.5 18 26 26 16 17.4 15.6 14.5 12 13.5 mV

*large Omten switch after 4 hours at 3amps: 13.2 13.5 12.3 18.6 15 14.4 13.5 11.5 13.2 12.9 mV

*6A ebay switch after 4 hours at 3amps: 6.2 5.3 5.2 5.6 5.1 6.1 4.9 6 5.2 5.5 mV

Nothing exiting yet, I thought that the small Omten had gotten a higher resistance, but after a few clicks it was back to what it was before the four-hour test.

6A test tomorrow! It was fun to build up the test-thing, but the testing itself turned out to be pretty boring to be honest .

Update: 6A results in post#14

Update: 10A results in post #17

Update: 16A results in post #25

What can I say but thanks. Looking forward to the results.

Thank you so much for doing this for us djozz! :bigsmile: This should put to rest many of my future switched build concerns.

This is great!

When I say the "typical large Omten swtich" i usually refer to this (PBS-101). PBS-101 is the one that is most common as far as I have seen. Not sure if its more durable than the one being tested (PBS-101C). Maybe we should start using proper names?



Assuming those are the real names.

I know, I should have one of those somewhere but can not find it. If I manage to find it tomorrow it will join the party at 6A :-)

I did not know the Omten switches had type nr's, if I can also find a type nr with the small Omten I will update the OP with them. Now sleep...

Subscribed, thanks for the testing!

Watching and waiting. Thanks djozz.

Thank you so much for doing this test! How come they rate these switches at 1.5A?

Nice, you are off to a great start here. Looking forward to the 6 amp and above test.

Cause they rate them at 250vAC

Just to be sure that i am on the same page + other people who are still trying to learn electronics,
“*6A ebay switch after 4 hours at 3amps: 6.2 5.3 5.2 5.6 5.1 6.1 4.9 6 5.2 5.5 mV”

These numbers are the voltage drop?
To calculate heat dissipated from the switch, I multiply the voltage drop, 6.2mV X 3A = 0.0186W?

Really interesting. Do you think you can do a test of a mcclicky or some high end switch to get a better point of reference? or some examples of bad switches? 0.02W seems like nothing to me, but is it a problem?
As time passes, the voltage/resistance gets lower right? “(the concensus was that long periods on high amps is what kills a switch, not the number of clicks)” So at a magic number of amps, the switch would actually increase in voltage? How come the resistance drops, but when it hits a certain amp, it would rise? Molecules vibrate faster and faster because of more and more heat Assumptions on top of assumptions lol…
Can anyone please explain a little on how this works? thanks!

sorry RaceR, I did not find that square Omten switch, that one will have to wait. But the set-up is so simple, I can just do another session with a new string of switches.

Started the 6A session almost an hour ago, no failures sofar. The small Omten measures 45mV at 6A, that is about 0.3W of heat it has to dissipate. We're getting somewhere :-)

At 6A, I just clamped the voltmeter over 1cm of the lead of the large Omten switch, and was a bit surprised to find 4.8mV, that stuff is not overly conductive!

You are correct, 0.0185W is nothing....yet. But the power increases with the current-square. I am now testing 6A, that generates 4 times the heat of 3A. The small switch does 0.3W already, and these switches are not designed for great heat dissipation.

At 3A, the resistance did not get lower over time, as was shown above , that was just about the first 20 seconds, and it could have something to do with the multimeter I am using (although both -very different- multimeters that I have show the same effect)

I am happy to torture any switch, but currently I don't have many different ones. If there's interest for it I can do a shopping session for a few more, but killing McClickies sounds a bit costly

Thank you for confirming my guess. I dont want you to kill an expensive switch! XD I just want to see the switch run at around 5A-6A so we can decide if spending an extra 6$ for an expensive clicky is really worth the gain. With your results so far, I would definitely buy an expensive switch because .3W is horrendous!
Have you taken apart the omten switches before? You can replace the parts inside with a copper cut sheets. instead of the original ones.

I only made one switch but it is now in a light that is permanently sealed ):
I also stretched the spring, and sandpapered the contacts to hopefully get better results.
I have 2 otmen switches comming in from FT. I will definitely try to post what I have done. But I do not know if it is any good. ):

ok, the 6A results are in, we got merely survivors! Despite the 0.3W heat even the small Omten went strong. I measured voltages over the switches at the beginning 10 clicks, halfway 10 clicks and at the end 10 clicks. No increasing resistances here, the small Omten even did a bit better at the end.

Small Omten 6A begin: 38 41 49 45 49 41 41 52 45 40 mV

6A 2hrs : 38 43 40 43 50 49 63 71 45 47 mV

6A 4hrs : 29 42 33 31 32 33 26 38 32 30 mV

Large Omten 6A begin: 22 24 22 22 21 25 22 26 21 23 mV

6A 2hrs : 18 30 23 32 25 25 25 31 24 26 mV

6A 4hrs : 18 31 25 32 23 22 24 20 21 29 mV

6A ebay sw. 6A begin: 10 13 12 10 12 15 13 11 13 12 mV

6A 2hrs : 9 13 13 12 12 11 14 12 11 12 mV

6A 4hrs : 11 13 13 13 16 13 14 15 13 13 mV

Started the 10A:

1.5 hours underway at 10A, no failed switches as yet. Did 10 clicks on each switch again: everything works normal, no increasing resistances yet. I don't know what you guys do with your switches but it sure looks like it is not current that kills this type of switch (these are switches with metal plates that are pushed onto the leads by a spring: the current is not flowing through the spring, see likevvii's post #13).

I did a very accurate temperature measurement (using my lips to sense the temperature ), the housing of the two bigger switches are luke-warm, the small switch is a bit warmer, all the leads, including the copper wires are pretty hot, but not 60degC+ hot.

The only switches I have killed have been some very junky stock switches that did not handle 10A. Ive never had an Omten switch fail in the 10-12A range. I have not gone higher on those switches. But I believe others have run them at around 15A.

Im curious to see the difference between the two omten switches in this test.

In my latest hot rod build, I have made my own "twisty switch". It should be good for lots and lots of amps, and then some.. I would not trust a typical Omten switch for what Im putting together.. J)

10A results. After four hours all three switches work fine. Over the small Omten there is a somewhat higher voltage variance in the end, but nothing I worry about. As said the small switch warms up more, but that does not seem to lead to failure yet. Of course for critical applications, like single li-ion cell lights it is nicer to have the larger switch because it causes a smaller voltage drop. In fact when using the small Omten at 10A the variance upon different clicks can be as high as 0.05V and that could be visible in the output of the light, or lead to a bit shorter period the driver stays in regulation.

What surpises me is that the voltage increase is not lineair with the current, it lags a bit behind, so the resistance decreases a bit when current increases (or because the temperature increases), which is good for the performance. Another thing that is good for the performance: as you can see with almost all 10 click voltage series, the first value is low compared to the average, it is the voltage reading before the first click, it means that if you leave the switch alone the resitance decreases somewhat over time.

Small Omten 10A begin : 54 56 70 59 57 62 60 55 59 55 mV

10A 1.5hrs: 39 62 54 64 61 68 51 56 60 63 mV

10A 4hrs : 55 73 79 100 92 62 52 49 93 51 mV

Large Omten 10A begin : 34 39 42 35 39 50 40 54 54 58 mV

10A 1.5hrs: 37 70 38 47 40 49 68 80 60 43 mV

10A 4hrs : 34 46 51 53 81 88 59 50 54 52 mV

6A ebay sw. 10A begin : 19 18 18 18 20 22 20 22 20 18 mV

10A 1.5hrs: 15 16 16 19 17 18 18 24 20 27 mV

10A 4hrs : 20 24 38 41 20 20 19 20 19 19 mV

All three switches make it to the 16A test! It has to wait a bit because my girldriend hates the sound of the fans, makes her think of bad airco days .

I can't help noticing that making a high amp switch is cheap and easy: a plastic housing with ballpoint click-mechanism, three pieces of metal, a spring. I can't comment much on the type of metal used, but these good performing Omten switches are not exactly using the metal with the best conductance.

Are you not sure that it is not the first comment that your girlfriend wants the testing stopped though you did clarify by saying they weren't very hot.

Sometimes I wonder about members here. Orsm testing, still, by the way. Thanks again.

She says that she still loves me, I think mostly despite of the hobby even though I did give her a flashlight two years ago (and she refused any more flashlights ever since, glad it was the good old Fenix E01 and not some crappy Ultrafire )